Method of producing lubricating oils



July 28, 1936. M. B. cHl'rTxcK 2,048,992

METHOD OF PRODUCING LUBRICATING OILS Filed Nov. '25, 1931 illlllllllllllllllll Arficlrer ww /MUZZM' Patented July 28, 1936 UNITED `STA'ES PATENT OFFICE METHOD F PROgIIJISING LUBRICATING Martin B.'Chittick, Chicago, Ill., assignor to 'Ifhe Pure Oil Company, Chicago, Ill., a. corporation of Ohio Application November 23, 1931, Serial No. 576,663

2 Claims.

5 cous hydrocarbon oil which is suitable for use as a lubricant either directly or by being blended with lubricating oils produced by other methods of diierent basic oils for the purpose of improving such latter oils when so blended.

Low boiling cracked oils, having substantially the boiling range characteristics of ordinary gasoline, and produced by high temperature or vapor phase conversion wherein high boiling oils in a vaporous state are heated to temperatures from l5 1000 F. to 1100a F., when subsequently condensed and collected, contain unsaturated hydrocarbons and certain highly reactive unsaturated hydrocarbons which if permitted to remain in the cracked oils, tend to form objectionable gums and color producing bodies, which render the oils unsuitable for use as motor fuels. In the removal of these offending unsaturated hydrocarbons, it is customary in the art to pass such low boiling oils into contact with a catalyst, such as fullers earth whereby .to eii'ect polymerization reactions to the end of polymerizing the objectionable compounds into compounds having higher molecular weights than those of the oils prior to such treatment. By thus changing the objectionable compounds into higher boiling compounds, sharp fractionation is provided so that the treated gum free oils may be separately removed and collected, substantially entirely free from the troublesome compounds.

Little or no use has been made of these high boiling polymerized residual oils removed from selective polymerization systems of the character set forth. I have found, however, that these higher boiling polymerized oils, containing the gum forming and color producing bodies, which are objectionable in a motor fuel distillate, can be treated to produce a lubricating oil having characteristics of approximately the following: A. P. I. 1.2-1.4".

Viscosity Saybolt universal 200 seconds at 210"v F., and that this oil, when blended with a partially dewaxed oil in the proportion of 2.2% has the property of reducing the pour test of such a. partially dewaxed oil from 35 F. to below 0 F.

In motor fuel lubricants, a low pour test is highly`desirable, particularly when motor vehicles are operated inv periods of cold weather. Refiners of lubricatingoils in order to produce oils of low pour test frequently resort to expensive apparatus such as refrigerating machinery, centrifuges and lters to remove from lubricating oils those wax-likel compounds which readily solidify at freezing temperatures. Such apparatus and ac- `companying processes add very considerably to 5 the cost of producing lubricating oil and, further, it has been found'that when the wax content of the oils has been substantially completely removed, it often results in diminishing the quality of the lubricants, as indicated by the low- 10 ering of the'temperature-viscosity characteristics thereof. I have found that ordinary lubricating oil need not be completely dewaxed in the manner which is now customary in producing a lubricating oil of good quality and having a low pour 15 point, but that a goodlyproportion of the wax may be retained in the oil, whereby upon the blending of this partially dewaxed oil with the oil produced in accordance with my invention, the resulting blending oil will `possess a desirably 59 low pour test and at the same time maintaining desired temperature-viscosity properties.

In producing my improved blending oil, I preferably employ a low boiling oil which may have the boiling range of gasoline, provided it is highly unsaturated as mentioned above, such unsaturation being the common characteristic of cracked motor fuel distillates produced lby high temperature or vapor phase conversion, and I mix with this oil a predetermined quantity of meao tallic halide such as anhydrous aluminum chloride. This mixture is then distilled with agitation to non-converting but ebullition temperatures, taking overhead through lassociated fractionating apparatus oils of the same boiling range as 35 charged to the distilling operation. Following the removal of the overhead products, I then remove from the distillation zone the higher boiling residual oils with the aluminum chloride, and 40 from this residual extract the aluminum chloride by water washing or other simple means. The oil, following removal of the aluminum chloride, then may be neutralized to remove any hydrochloric acid remaining, and the resultant product has the properties of the lubricating oil given in the above table.

While my process is not in any way dependent on any particular type of apparatus, there has been shown in the'accompanying drawing diagrammatically certain apparatus which may be employed in carrying the process, comprising the presentinvention, into practical operation.

In the drawing. the numeral I designates a still which includes the usual drum 2, a fire box Lil 3 and a burner 4. Any suitable still may be employed however, such as standard types of shell or tube stills, although the still illustrated may be employed in the operation of my process quite advantageously.

The interior of the still is provided with a shaft 5 driven by an externally located motor 6, and the bottom of the shaft carries a stirrer or agitator 1. A tank 8 may be employed to receive the charging stock comprising the oils to be treated. As stated, this oil or charging stock consists preferably of a low boiling distillate obtained from a vapor phase cracking operation. In such an operation, cracking temperatures of the order of from 1000o F. to 1100 F. are employed, which result in the production of a low boiling distillate, falling within the boiling range of ordinary gasoline and characterized by the high percentage of unsaturated hydrocarbons which it contains. This charging stock may-be passed from the tank 8 by way of a pipe line-.9 into the interior of the drum 2. Approximately .5% by weight of anhydrous aluminum chloride is added to the oil in the still and the resulting mixture is then subjected to the heat of distillation. This distillation is preferably carried on slowly and proper contact is maintained between the catalyst andthe oils contained in the still by the rotation of the agitator 1, or by the operation of an equivalent mechanism- The vapors which are developed by this distillationpass from the top of the drum by Way of an overhead line I and enter a separator II. Entrained high boiling oils present in the vapors collect in the bottom of the separator and are returned to the still for further heat treatment by the reux pipe line I2. The vapors which leave the top of the separator or fractionator may then be condensed in the coil I3 and the resulting condensate collected in a tank I4 as finished motor fuel oil. The amount of the aluminum chloride used in the process is of course subject to variation but I preferably employ ,5% by weight although in the treatment of certain oils,-the percentage may be as high as by weight. Control of the reactions may be secured byvarying the amount of the aluminum chloride, the rate of distillation and the temperatures used. The vaporous products which pass overhead from the still are substantially free from those unsaturated compounds which produce gums while the distillates are later exposed to light and air.

Various operating pressures may be used in the still, ranging from atmospheric to pressures of the order of several hundred pounds per square inch. Also the temperature range of the oils heated in the still I may vary within a range of approximately 200 F. to 500 F. The oils collected in the tank I4 constitute a clear motor fuel spirit having the boiling range of ordinary gasoline and are stable and gum free, being suitable for commercial distribution and use. 'Ihe oils collected in the tank `I4 are substantially the same boiling range as those charged to the still, but the operation is such in the still that polymerization of the undesired compounds takes place, with the'result that the residual oils removed from the still through the line l5, together with the catalyst possess a boiling range materially higher than those oils charged to the still. This mixture of high boiling oils and aluminum chloride passes from the line I5 into an orice mixer I6, water entering the line I5 as at I1. 'I'he mixture discharged from thel orlce -mixer is delivered toa separator I8. chloride is removed as at I9 from the bottom of the separator while the oils are separately removed by way of a line 20. To remove anyhydrochloric acid which might be present .in the oils as a result of the addition of water, an alkali, such 5 as caustic soda is introduced into the oils passing through the line by way of the line 2|, and the mixture is then passed through a second orifice mixer 22 and thence into the separator 23. The finished oil is transferred from the separator by way of a line 24 to a storage tank 25.

'I'he oil received in the tank 25 has been found to possess the following properties:

Gravity A. P. I. 1214.

VlscositySaybolt universal 200 seconds at 210 F. `This oil, as stated, possesses unusual properties in that it may be added in relatively small quantities (in the proportion of 2.2%, by weight) to a partially dewaxed lubricating oil for the purpose of permitting such a partially dewaxed oil to flow 20 freely at low temperatures and at the same time preserving the full lubricating value ofthe partially dewaxed oil when the latter is subjected to elevated temperatures under actual conditions of use in an internal combustion engine.

I am aware of the disclosures in -the patent to Davis 1,815,022 and do not claim as my invention anything disclosed in that patent regarding the use of a blending material for partially ,dewaxed lubricating oil formed by the condensation of a waxy hydrocarbon material with an aromatic hydrocarbon material, my invention residing principally in the formation of a blending stock for lubricating oils wherein the blended stock is produced from highly unsaturated hydrocarbons and especially those hydrocarbons obtained as a. residual oil during the treatment of cracked low boiling hydrocarbon oils, composed of unsaturated hydrocarbons, with aluminum chloride to remove objectionable compounds therefrom in the form of gum and color producing bodies.

It will be understood that I do not limit myself to the particular type of still disclosed but reserve the right to employ any standard still of the intermittent or continuous types, now commonly used in oil treating operations. In the event a tube still is employed, aluminum chloride may be placed in foraminated containers, either alone or admixed with fullers earth to the end of providing extensive surface contact between the heated products of a tube still and the aluminum chloride. Also the aluminum chloride Y may be passed in unison with the oils through a tube still, but in this operation care should be exercised to prevent the aluminum chloride from collecting and depositing on the heated walls of the tube and building up hardened deposits of an obstructing nature. Agitators placed in tubes may be used to prevent this condition.

Obviously other changes from a mechanical C" standpoint might be resorted to for carrying out my process which are apparent to those skilled in the art of treatingoils nd I therefore contemplate the use of any oy all of such variations 'y which might be said to fait fairly within the scope 3" of the following claims/l What is claimed isr/ 1. A low pour point lubricant Vcomprising partially dewaxed lubricating oil admixed with a relatively small amount of oil having a gravity 7" (A. P. I.) of 12-14 and Saybolt universal viscosity of 200 seconds at 210 F., said oil being the residual obtained from distilling unrened vapor phase cracked gasoline with ,aluminum 7F chloride at a temperature up to 500 F.

2. A method for simultaneously refining gasoline and producing a low pour test lubricating oil which comprises subjecting unrened gasoline resulting from cracking higher boiling oils in the vapor phase at temperatures of the order of 1000 to 1100 F. to agitation with a relatively small amount of aluminum chloride sulcient to-polymerize the gum-forming constituents therein to desirable lubricating oil material at a temperature up to 500 F. and simultaneously distilling oi! hydrocarbons boiling within the gasoline range substantially free from gum forming constituents, and subjecting the residual oil to successive water washing, caustic alkali, and fuller's earth treatment to produce a iinished lubricating oil blending stock.

MARTIN B. CHITI'ICK. 

